METHOD FOR MANUFACTURING COAL BRIQUETTES, AND
APPARATUS FOR MANUFACTURING SAID COAL BRIQUETTES
Technical Field
The present invention relates to a method and an apparatus for
manufacturing coal briquettes. More particularly, the present invention relates
to a method and an apparatus for manufacturing coal briquettes capable of
implementing excellent hot strength by using graphite.
10 【Background Art】
In a smelting reduction iron-making method, a reducing furnace for
reducing iron ore and a melter-gasifier for melting reduced iron ore are used.
In the case of melting iron ores in the melter-gasifier, as a heat source to melt
iron ores, coal briquettes are charged into the melter-gasifier. Here, reduced
15 iron is melted in the melter-gasifier, transformed to molten iron and slag, and
then discharged outside. The coal briquettes charged into the melter-gasifier
form a coal-packed bed. After oxygen is injected through a tuyere installed at
the melter-gasifier, the coal-packed bed is combusted to generate combustion
gas. The combustion gas is transformed into a hot reducing gas while rising
20 through the coal-packed bed. The hot reducing gas is discharged outside the
melter-gasifier to be supplied to the reducing furnace as the reducing gas.
In the case of using the coal briquettes, additional control means is
necessary to make a process for manufacturing molten iron efficient by
3
increasing yield of molten iron and reducing fuel ratio. To this end,
differentiation capacity in the melter-gasifier of the coal briquettes is reduced
and thus the coal briquettes in the melter-gasifier need to be maintained with a
large grain size. In this case, reaction efficiency and heat-transfer efficiency
between materials may increase by ensuring permeability 5 and flow so that gas
and liquid smoothly pass through the melter-gasifier. Further, a generation
amount of fine powder which is not efficiently used due to differentiation during
manufacture of molten iron may be reduced. There is a limitation in reduction
of generating amount of fine powers by mixing of various kinds of coals.
10 【DISCLOSURE】
【Technical Problem】
A method for manufacturing coal briquettes having excellent hot
strength is provided. Further, an apparatus for manufacturing coal briquettes
having excellent hot strength is provided.
15 【Technical Solution】
A method for manufacturing coal briquettes according to an exemplary
embodiment of the present invention is applied to be charged into a dome part
of a melter-gasifier to be rapidly heated in an apparatus for manufacturing
molten iron including the melter-gasifier into which reduced iron is charged, and
20 a reducing furnace connected to the melter-gasifier and providing the reduced
iron. A method for manufacturing coal briquettes according to an exemplary
embodiment of the present invention includes i) providing powdered coals; ii)
providing graphite suppressing hot differentiation of the coal briquettes; iii)
4
providing a hardening agent and a binder; iv) providing a mixture by mixing the
powdered coals, the graphite, the hardening agent, and the binder; and v)
providing the coal briquettes by molding the mixture. In the providing of the
mixture, a ratio of the amount of graphite to the sum of the amount of powdered
coals and the amount of graphite is greater 5 than 0 and 0.3 or less.
The ratio of the amount of graphite to the sum of the amount of
powdered coals and the amount of graphite may be 0.1 to 0.15. The graphite
may be crystalline graphite or kish graphite. In the providing of the graphite,
the graphite may be pressure-transported with a gas, stored in a graphite
10 storage bin, and then provided. In the providing of the mixture, the graphite
may be directly mixed with the hardening agent and the binder while not mixed
with the powdered coals in advance. The gas may include nitrogen or a byproduct
gas.
In the providing of the mixture, the amount of binder may increase as
15 the amount of graphite increases. In the providing of the coal briquettes, the
coal briquettes may have an X-ray peak at 26 to 27 degrees when the coal
briquettes are under X-ray diffraction analysis.
An apparatus for manufacturing coal briquettes according to an
exemplary embodiment of the present invention includes i) a powdered coal
20 storage bin storing powdered coal; ii) a graphite storage bin storing graphite; iii)
a graphite transport pipe connected with the graphite storage bin and pressuretransporting
the graphite with a gas to the graphite storage bin; iv) a binder
storage bin storing a binder; v) a hardening agent storage bin storing a
hardening agent; vi) a mixer providing a mixture by mixing the powdered coal
5
supplied from the powdered coal storage bin, the graphite supplied supplied
from the graphite storage bin, the binder supplied from the binder storage bin,
and the hardening agent supplied from the hardening agent storage bin; and vii)
a molding machine receiving the mixture from the mixer to mold the mixture.
The graphite storage bin may be directly connected 5 with the mixer.
【Advantageous Effects】
Since the coal briquettes are manufactured by using graphite, cold
strength and hot strength of the coal briquettes may be largely improved. That
is, it is possible to improve both size and strength of char obtained when the
10 coal briquettes are drastically pyrolyzed in the melter-gasifier by using graphite.
Further, it is possible to improve operation efficiency by using the coal
briquettes with added graphite in a process for manufacturing molten irons.
【Description of the Drawings】
FIG. 1 is a schematic flowchart of a method for manufacturing coal
15 briquettes according to an exemplary embodiment of the present invention.
FIG. 2 is a schematic diagram of an apparatus for manufacturing coal
briquettes according to an exemplary embodiment of the present invention.
FIG. 3 is a schematic diagram of a apparatus for manufacturing molten
irons connected to the apparatus for manufacturing coal briquettes of FIG. 2.
20 FIG. 4 is a schematic diagram of another apparatus for manufacturing
molten irons connected to the apparatus for manufacturing coal briquettes of
FIG. 2.
FIG. 5 shows a photograph of coal briquettes manufactured according to
6
Experimental Example 5 and a photograph of char obtained by heating the coal
briquettes.
FIG. 6 is an X-ray diffraction graph of coal briquettes manufactured
according to Experimental Examples 10 to 13 and Comparative Example 1.
5 【Mode for Invention】
Terms such as first, second, and third are used to illustrate various
portions, components, regions, layers, and/or sections, but not to limit them.
These terms are used to discriminate the portions, components, regions, layers
or sections from the other portions, components, regions, layers, or sections.
10 Therefore, a first portion, component, region, layer, or section as described
below may be a second portion, component, region, layer, or section within the
scope of the present invention.
It is to be understood that the terminology used therein is only for the
purpose of describing particular embodiments and is not intended to be limiting.
15 It must be noted that, as used in the specification and the appended claims, the
singular forms include plural references unless the context clearly dictates
otherwise. It will be further understood that the terms "comprises" and/or
"comprising," when used in this specification, specify the presence of stated
properties, regions, integers, steps, operations, elements, and/or components,
20 but do not preclude the presence or addition of one or more other properties,
regions, integers, steps, operations, elements, and/or components thereof.
Unless it is mentioned otherwise, all terms including technical terms and
scientific terms used herein have the same meaning as the meaning generally
understood by the person with ordinary skill in the art to which the present
7
invention belongs. The terminologies that are defined previously are further
understood to have the meanings that coincide with related technical
documents and the contents that are currently disclosed, but are not to be
interpreted as the ideal or very official meaning unless it is defined otherwise.
The present invention will be described more 5 fully hereinafter with
reference to the accompanying drawings, in which exemplary embodiments of
the invention are illustrated. As those skilled in the art would realize, the
described embodiments may be modified in various different ways, all without
departing from the spirit or scope of the present invention.
10 Hereinafter, the term "graphite" means a material that belongs to a
hexagonal system, has a plate-like crystal, and has a black color and a metallic
luster. Further, it is understood that graphite includes both natural graphite
and graphite manufactured artificially.
FIG. 1 schematically illustrates a flowchart of a method for
15 manufacturing coal briquettes according to an exemplary embodiment of the
present invention. The method for manufacturing coal briquettes in FIG. 1 is
just to exemplify the present invention, and the present invention is not limited
thereto. Accordingly, the method for manufacturing coal briquettes may be
variously modified.
20 As illustrated in FIG. 1, the method for manufacturing coal briquettes
includes providing powdered coal (S10), providing graphite (S20), providing a
hardening agent and a binder (S30), providing a mixture by mixing the
powdered coal, the graphite, the hardening agent, and the binder (S40), and
providing coal briquettes by molding the mixture (S50). In addition, if
8
necessary, the method for manufacturing coal briquettes may further include
other processes.
First, in step S10, the powdered coal is supplied. The powdered coal
may be supplied by separating raw coals according to a grain size. For
example, raw coal with a grain size of 8mm or less may 5 be supplied as the
powdered coal. That is, the raw coals are separated according to a grain size
to be sorted into powdered coal having a small grain size and lump coal having
a large grain size. Coal briquettes having excellent cold strength may be
manufacture by using powdered coal having a small grain size as the raw coal.
10 The lump coal which is raw coal with a grain size of more than 8mm may be
directly charged into the melter-gasifier or crushed to be used. Meanwhile,
although not illustrated in FIG. 1, in order to improve the quality of molten iron,
coal for quality control may be mixed with the powdered coal. Here, as the
coal for quality control, coal with reflectance of a predetermined value or more
15 may be used.
Next, in step S20, the graphite is provided. As the graphite, natural
graphite, crystalline graphite, kish graphite, and the like may be used. Here,
the kish graphite is discharged as a by-product of an iron making process. A
grain diameter and strength of char generated by charging coal briquettes into
20 the melter-gasifier are improved by adding the graphite to the coal briquettes.
The coal included in the coal briquettes charged into the melter-gasifier is
differentiated while a crack is generated by shrinkage and swelling thereof.
Accordingly, in order to prevent generation and propagation of the crack,
thermally stable graphite is added to the coal briquettes. Since the graphite is
9
thermally stable, it stably exists during swelling and contraction of coals in the
coal briquettes. Accordingly, since the graphite plays a role similar to an
aggregate used in making concrete or mortar, the coal briquettes may be
efficiently prevented from being differentiated at a high temperature by the
5 graphite.
The grain diameter of char of the coal briquettes increases by adding
graphite. The increasing of the grain diameter of char means that the hot
strength of the coal briquettes is improved because the coal briquettes are not
differentiated well in the melter-gasifier. The graphite is composed of carbon,
10 and in the graphite, a hexagonal benzene-ring structure is very well developed
as compared with other coal. That is, as a polycyclic carbon structure close to
the graphite is developed, a capacity to transfer electrons or heat in the coal
briquettes rapidly increases by the polycyclic carbon structure in a plane. Heat
conductivity of the coal increases as the degree of coalification increases. For
15 example, heat conductivity (: W·m-1·K-1) of bituminous coal which is used
mainly for iron making is 1 or slightly higher than 1. In contrast, heat
conductivity of graphite has several tens of times higher value than that of
bituminous coal. That is, the graphite has a very high heat transfer rate. The
coal briquettes are differentiated at a high temperature by a heat transfer
20 characteristic. That is, when a reaction in which the coal briquettes are
pyrolyzed to generate char is divided into many steps, in the coal briquettes at
room temperature charged into the hot melter-gasifier, a heat transfer
phenomenon from the surface to the inside thereof occurs. Accordingly, even
in the case where a surface portion of coal briquettes reaches a high
10
temperature of 1000℃, the inside of the coal briquettes exists at a temperature
much lower than 1000℃. A difference in temperature between the inside and
the outside of the coal briquettes causes a difference in contraction ratio, and
cracks occur due to the difference in contraction ratio for each portion of the
coal briquettes. Accordingly, finally, char having a small 5 grain diameter is
manufactured. That is, as a temperature difference increases, a differentiation
phenomenon increases.
When a graphite with high heat conductivity and a very low thermal
expansion rate is added to the coal briquettes, a temperature difference in the
10 coal briquettes is reduced. That is, when the graphite is added, the
temperature of the entire coal briquettes is further uniformalized. Accordingly,
since the cracks may be suppressed according to a change in a contraction rate
due to the temperature difference of the coal briquettes, the coal briquettes are
not differentiated into small pieces but exist with a large grain diameter.
15 Further, even if the crack occurs in the char, thermally stable graphite
suppresses the crack from being propagated. Accordingly, even when the coal
briquettes are drastically heated, the coal briquettes are differentiated into large
grains or char maintaining the shape of the coal briquettes as it is can be
manufactured. In the case of manufacturing the coal briquettes by adding
20 graphite according to the aforementioned principle, the grain diameter of char
obtained from the coal briquettes which are drastically pyrolyzed is great and
the strength thereof is also high.
Meanwhile, the graphite is pressure-transported by a gas and may be
11
stored in a graphite storage bin. Here, in order to prevent the ignition of the
graphite, nitrogen or a by-product gas may be used as the gas. When the coal
briquettes are manufactured, the graphite stored in the graphite storage bin may
be sent out to be used.
Next, in step S30, the hardening agent and the binder 5 are provided. As
the hardening agent, quicklime, slaked lime, a metal oxide, fly ash, clay, a
surface active agent, a cationic resin, an accelerator, fiber, phosphate, sludge,
waste plastics, waste lubricating oil, and the like may be used. Further, as the
binder, molasses, starch, sugar, a polymer resin, pitch, tar, bitumen, oil, cement,
10 asphalt, water glass, or the like may be used. For example, when the coal
briquettes are manufactured by using molasses as the binder and quicklime as
the hardening agent, the cold strength of coal briquettes may be largely
increased by a saccharate bond.
Next, in step S40, the mixture is provided by mixing the powdered coal,
15 the graphite, the hardening agent, and the binder. Here, the powdered coal,
the graphite, the hardening agent, and the binder may be mixed in a random
order or specific materials among those may be first mixed. For example, after
the powdered coals and the graphite are first mixed, the binder may be mixed
and then the hardening agent may be mixed. Alternatively, the graphite may
20 be directly mixed with the hardening agent and the binder while being not mixed
with the powdered coals in advance. That is, since dried coke dust in the
graphite does not need to be mixed with the powdered coal in advance by
controlling a water amount included therein, the graphite may be directly mixed
with the hardening agent and the binder.
12
When a large amount of graphite is added to the coal briquettes, a
usage amount of molasses or bitumen as the binder needs to increase in order
to bind the graphite and the powdered coal. That is, as the amount of graphite
increases, the amount of binder needs to increase. In the case of adding the
graphite while the amount of binder is small, it is difficult 5 to mold the coal
briquettes and the room-temperature strength of the coal briquettes is lowered.
Accordingly, when the coal briquettes are transported or stored, the coal
briquettes are differentiated. That is, when the amount of the binder is too little
or too great, the cold strength of the coal briquettes deteriorates. Accordingly,
10 the amount of the binder included in the mixture is controlled in the
aforementioned range. For example, the amount of the binder included in the
mixture may be controlled to 8.5wt% to 9wt%.
Meanwhile, although not illustrated in FIG. 1, the raw coal is
manufactured by mixing the powdered coal and the graphite in advance and
15 then may be mixed with the hardening agent and the binder. The
manufactured raw coals may be separated into coals with a predetermined
grain size or more. In addition, the grain size of the raw coal may be controlled
to be suitable for manufacturing the coal briquettes by crushing the sorted raw
coals. That is, the powdered coals and the graphite are crushed to be
20 provided as the raw coal.
A ratio of the amount of graphite to the sum of the amount of powdered
coal and the amount of graphite may be greater than 0 and 0.3 or less. When
the amount of graphite is too great, the cold strength of the coal briquettes is
lowered. Accordingly, the amount of graphite is controlled in the
13
aforementioned range. More preferably, the ratio of the amount of graphite to
the sum of the amount of powdered coals and the amount of graphite may be
0.1 to 0.15.
Finally, in step S50, the coal briquettes are provided by molding the
mixture. For example, the coal briquettes may 5 be manufactured by
continuously compacting the mixture by using a molding machine including a
pair of rollers.
The coal briquettes include carbons. Accordingly, when an X-ray
diffraction analysis of the coal briquettes is performed, the coal briquettes have
10 X-ray peak 2 at 26 to 27. Preferably, the coal briquettes have X-ray peak
2 at 26.6.
Generally, a method of improving the hot strength of the coal briquettes
by using the binder such as bitumen has been attempted. However, since the
coal briquettes are differentiated at a high temperature, efficient means and
15 methods capable of increasing the grain diameter and the strength of the char
are required. Further, even though coal is changed in its type, it is difficult to
improve the hot strength of the coal briquettes.
FIG. 2 schematically illustrates a apparatus for manufacturing coal
briquettes 100 according to another exemplary embodiment of the present
20 invention. The apparatus for manufacturing coal briquettes 100 in FIG. 2 is
just to exemplify the present invention, and the present invention is not limited
thereto. Accordingly, a structure of the apparatus for manufacturing coal
briquettes 100 may be variously modified.
As illustrated in FIG. 2, the apparatus for manufacturing coal briquettes
14
100 includes a powdered coal storage bin 10, a coal for quality control storage
bin 20, a graphite storage bin 30, a binder storage bin 40, a hardening agent
storage bin 50, a mixer 60, and a molding machine 70. In addition, the
apparatus for manufacturing coal briquettes 100 further includes a crusher 80, a
mixed coal storage bin 92, a collected coal storage bin 94, 5 a graphite transport
pipe 303, a graphite carrying device 305, and separators 801, 803, and 805. If
necessary, the apparatus for manufacturing coal briquettes 100 may further
include other devices. Since a detailed structure and an operation method of
respective devices included in the apparatus for manufacturing coal briquettes
10 100 of FIG. 2 can be easily understood by those skilled in the art, the detailed
description is omitted.
The powdered coal is stored in the powdered coal storage bin 10. In
addition, the coal for quality control may be used in order to improve the quality
of the coal briquettes and are stored in the coal for quality control storage bin 20.
15 The coal passes through the separator 801 to be divided into lump coal and
powdered coal, and then the powdered coal may be stored in the powdered
coal storage bin 10. For example, coal with a grain size of 8 mm or less may
be used as powdered coal. Meanwhile, the lump coal separated by the
separator 801 may be directly charged into a melter-gasifier 210 (illustrated in
20 FIG. 3).
As illustrated in FIG. 2, the graphite storage bin 30 stores the graphite
supplied from the graphite carrying device 305 through the graphite transport
pipe 303. For example, a tank lorry and the like may be used as the graphite
carrying device 305. The graphite is pressure-transported by a gas and stored
15
to be supplied in the graphite storage bin 30 from the graphite carrying device
305. In this case, nitrogen or a by-product gas is used as the gas to prevent
ignition of the graphite. The by-product gas is a gas generated during a
process in a steel mill. The graphite is directly mixed with the hardening agent
and the binder without being mixed with the powdered 5 coal in advance.
Meanwhile, in order to prevent abrasion by the graphite during transport,
the graphite transport pipe 303 may be used by manufacturing the pipe itself
with a specific material or coating an inner side of the pipe with basalt or the like.
Since the graphite is stored and transported in a large sack, it is preferred that
10 the graphite is loaded for being used in the graphite carrying device 305, but the
graphite may be stored in the graphite storage bin 30 by directly removing the
sack.
The mixed coal is separated in the separator 803 and the mixed coal
with a predetermined grain size or more is crushed by the crusher 80. The
15 crushed mixed coal and the mixed coal with less than a predetermined grain
size are stored in the mixed coal storage bin 92. The mixed coal stored in the
mixed coal storage bin 92 is provided to the mixer 60.
As illustrated in FIG. 2, the binder is stored in the binder storage bin 40.
The binder binds the powdered coal and the graphite to each other to be made
20 into a state suitable for manufacturing the coal briquettes. The binder storage
bin 40 is connected with the mixer 60 to provide the binder thereto.
Meanwhile, the hardening agent is stored in the hardening agent
storage bin 50. The hardening agent is coupled with the powdered coal, the
graphite, and the binder to harden the coal briquettes and thus the strength of
16
coal briquettes may be optimized. The hardening agent storage bin 50 is
connected with the mixer 60 to provide the hardening agent to the mixer 60.
The mixer 60 mixes the powdered coal, the graphite, the binder, the
hardening agent, and the like with each other to provide the mixture for
manufacturing the coal briquettes. Meanwhile, the graphite 5 storage bin 30 is
directly connected with the mixer 60 to provide the graphite to the mixer 60.
Since the water and the grain size of the graphite are controlled, the graphite
may be immediately used in the mixer 60.
As illustrated in FIG. 2, the molding machine 70 includes a pair of rolls
10 that rotate in opposite direction to each other. The mixture is compacted by
the pair of rolls by providing the mixture therebetween to manufacture the coal
briquettes. Meanwhile, the powdered coal is stored in the collected coal
storage bin 94 by separating the manufactured coal briquettes through the
separator 805 again. The powdered coal stored in the collected coal storage
15 bin 94 is re-supplied to the mixer 60 again to be used as a raw material of the
coal briquettes. As a result, use efficiency of the powdered coal may be
improved.
FIG. 3 schematically illustrates an apparatus for manufacturing molten
iron 200 which is connected to the apparatus for manufacturing coal briquettes
20 100 of FIG. 2 and uses the coal briquettes obtained by the apparatus for
manufacturing coal briquettes 100. A structure of the apparatus for
manufacturing molten iron 200 in FIG. 3 is just to exemplify the present
invention, and the present invention is not limited thereto. Accordingly, the
apparatus for manufacturing molten iron 200 in FIG. 3 may be modified in
17
various shapes.
The apparatus for manufacturing molten iron 200 in FIG. 3 includes a
melter-gasifier 210 and a reducing furnace 220. In addition, if necessary, the
apparatus for manufacturing molten iron 200 may include other devices. Iron
ore is charged into and reduced in the reducing furnace 5 220. The iron ore
charged into the reducing furnace 220 is dried in advance and then prepared as
reduced iron while passing through the reducing furnace 220. The reducing
furnace 220 with a packed bed type, receives the reducing gas from the meltergasifier
210 to form a coal-packed bed therein.
10 Since the coal briquettes manufactured by the apparatus for
manufacturing coal briquettes 100 of FIG. 2 are charged into the melter-gasifier
210 of FIG. 3, a coal-packed bed is formed in the melter-gasifier 210. A dome
part 2101 is formed in an upper portion of the melter-gasifier 210. That is, in
the dome part 2101 having a wider space than another part of the melter15
gasifier 210, hot reducing gas exists. The coal briquettes are charged into the
dome part 2101 of the melter-gasifier 210 and then rapidly heated to fall down
to the lower portion of the melter-gasifier 210. Char generated by a pyrolysis
reaction of the coal briquettes moves to the lower portion of the melter-gasifier
210 to exothermic-react with oxygen supplied through a tuyere 230. As a
20 result, the coal briquettes may be used as a heat source which keeps the
melter-gasifier 210 at a high temperature. Meanwhile, since the char provides
permeability, a large amount of gas generated from the lower portion of the
melter-gasifier 210 and reduced iron supplied from the reducing furnace 220
may more easily and uniformly pass through the coal-packed bed in the melter18
gasifier 210.
In addition to the aforementioned coal briquettes, if necessary, lump
carbon ash or coke may be charged into the melter-gasifier 210. The tuyere
230 is installed at an outer wall of the melter-gasifier 210 to inject oxygen.
Oxygen is injected into the coal-packed bed to form a 5 raceway. The coal
briquettes are combusted in the raceway to generate a reducing gas.
FIG. 4 schematically illustrates another apparatus for manufacturing
molten irons 300 which is connected to the apparatus for manufacturing coal
briquettes 100 of FIG. 2 and uses the coal briquettes manufactured by the
10 apparatus for manufacturing coal briquettes 100. A structure of the apparatus
for manufacturing molten iron 300 in FIG. 4 is just to exemplify the present
invention, and the present invention is not limited thereto. Accordingly, the
apparatus for manufacturing molten iron 300 in FIG. 4 may be modified in
various shapes. Since the structure of the apparatus for manufacturing molten
15 iron 300 in FIG. 4 is similar to the structure of the apparatus for manufacturing
molten iron 200 in FIG. 3, like reference numerals are used in like parts, and the
detailed description thereof is omitted.
As illustrated in FIG. 4, the apparatus for manufacturing molten iron 300
includes a melter-gasifier 210, a reducing furnace 310, a device for compacting
20 reduced iron 320, and a compacted reduced iron storage bin 330. The
compacted reduced iron storage bin 330 may be omitted.
The manufactured coal briquettes are charged into the melting gasifier
210. Here, the coal briquettes generate reducing gas in the melter-gasifier 210
and the generated reducing gas is supplied to the fluidized-bed reducing
19
furnace 310. Fine iron ore is supplied to the fluidized-bed reducing furnace
310 and manufactured to reduced iron while fludizing by the reducing gas
supplied to the fluidized-bed reducing furnace 310 from the melter-gasifier 210.
The reduced iron is compacted by the device for compacting reduced iron 320
and stored in the compacted reduced iron storage bin 5 330. The compacted
reduced iron is supplied from the compacted reduced iron storage bin 330 to
the melter-gasifier 210 to be melted therein. Since the coal briquettes are
supplied to the melter-gasifier 210 to be transformed to char having permeability,
a large amount of gas generated from the lower portion of the melter-gasifier
10 210 and the compacted reduced iron more easily and uniformly pass through
the coal-packed bed in the melter-gasifier 210 to manufacture molten iron with
good quality. Meanwhile, oxygen is supplied through the tuyere 230 to
combust the coal briquettes.
Hereinafter, the present invention will be described in more detail
15 through experimental examples. The experimental examples are just to
exemplify the present invention, and the present invention is not limited thereto.
Experimental Example
Experiment for measuring size of char of coal briquettes
A mixture was manufactured by mixing coal and graphite. Molasses
20 was mixed in the mixture at 8.5 parts by weight based on 100 parts by weight of
the mixture to manufacture coal briquettes. In addition, in order to evaluate the
coal briquettes charged through a hot dome part of a melter-gasifier, 1000g of
coal briquettes were charged into a reaction tube maintained at 1000 C and
heat-treated for 60 minutes while rotating at 10 rotations per minute. In
20
addition, the coal briquettes obtained by heat treatment were separated. A hot
strength index of coal briquettes was evaluated by representing a percentage of
a weight of char passed through a sieve opening of 10mm or more with respect
to a weight of the entire char. The experimental result is represented in the
5 following Table 1.
Experimental Example 1
Coal briquettes were manufactured by using coal A which was weak
coking coal without coking force. An amount of volatile matter of coal A was
35%. When the coal briquettes were manufactured by adding graphite of
10 10wt%, a grain diameter of char of the coal briquettes increased. That is, a
ratio of the char of the coal briquettes with a grain diameter of char of the coal
briquettes of 10 mm or more rapidly increased to 77.7%.
Experimental Example 2
Coal briquettes were manufactured by using coal A which was weak
15 coking coal without coking force. An amount of volatile matter of coal A was
35%. When the coal briquettes were manufactured by adding graphite of
15wt%, a grain diameter of char of the coal briquettes increased. That is, a
ratio of the char of the coal briquettes with a grain diameter of char of the coal
briquettes of 10 mm or more rapidly increased to 91.2%.
20 Experimental Example 3
Coal briquettes were manufactured by using coal A which was weak
coking coal without coking force. An amount of volatile matter of coal A was
35%. When the coal briquettes were manufactured by adding graphite of
30wt%, a grain diameter of char of the coal briquettes slightly increased. That
21
is, a ratio of the char of the coal briquettes with a grain diameter of char of the
coal briquettes of 10mm or more rapidly increased to 89%.
Experimental Example 4
Coal briquettes were manufactured by using coal B which was coking
coal having a large coking force. An amount of volatile 5 matter of coal B was
25%. When the coal briquettes were manufactured by adding graphite at
10wt%, a grain diameter of char of the coal briquettes increased. That is, a
ratio of the char of the coal briquettes with a grain diameter of char of the coal
briquettes of 10mm or more rapidly increased to 72.9%.
10 Experimental Example 5
Coal briquettes were manufactured by using coal B which was coking
coal having a large coking force. An amount of volatile matter of coal B was
35%. When the coal briquettes were manufactured by adding graphite at
15wt%, a grain diameter of char of the coal briquettes increased. That is, a
15 ratio of the char of the coal briquettes with a grain diameter of char of the coal
briquettes of 10 mm or more rapidly increased to 93.2%.
FIG. 5(a) is a photograph of coal briquettes manufactured according to
Experimental Example 5, and FIG. 5(b) is a photograph of char obtained by
heat-treating the coal briquettes of FIG. 5 (a).
20 As illustrated in FIG. 5, the char in which the shape of the coal
briquettes was almost left as it is was manufactured. That is, a ratio of char of
the coal briquettes with a grain diameter of 10 mm was 93.2%, and the grain
diameter of the char was maintained almost the same as the grain diameter of
the coal briquettes before heat treatment.
22
Comparative Example 1
For comparison with the experimental examples, coal briquettes were
manufactured by only coal A without adding graphite. The experimental
processes were the same as those of the aforementioned Experimental
Example 1. In this case, in the size of the char of the obtained 5 coal briquettes,
since a ratio of large grains of 10 mm or more was very low at 12.3%, it could
be seen that the coal briquettes were rapidly pyrolyzed to be differentiated into
small pieces.
Comparative Example 2
10 Coal briquettes were manufactured by using coal A which was weak
coking coal without coking force. An amount of volatile matter of coal A was
35%. When the coal briquettes were manufactured by adding graphite at
40wt%, a grain diameter of char of the coal briquettes was slightly decreased.
That is, a ratio of char of the coal briquettes with a grain diameter of the char of
15 the coal briquettes of 10 mm or more as 83.8 % was reduced as compared with
a ratio of char of coal briquettes of Experimental Examples 1 to 5. Accordingly,
it could be seen that an adding effect of graphite was deteriorated. The
aforementioned Experimental Examples 1 to 5 are represented in the following
Table 1 by comparing them with Comparative Examples 1 and 2.
20 Experiment for measuring strength of char of coal briquettes
A mixture was manufactured by mixing coals and graphite. Molasses
was mixed in the mixture at 8.5 parts by weight based on 100 weights of the
mixture to manufacture coal briquettes. In addition, when coal briquettes
charged through a hot dome part of a melter-gasifier were transformed to char,
23
an experiment was performed in order to verify whether the strength of char
was deteriorated according to an increase in size of the char. The strength of
the char was evaluated under the same conditions as a hot strength (CSR)
measuring method of coke for metallurgy used in a blast furnace. The char
was put in an I-type drum for measuring the hot strength 5 (CSR) of coke and
rotated 600 times at 20rpm, and then the content of the remaining char with a
size of 10mm or more was measured. Here, a length of the I-type drum was
600mm. The experimental result is represented in the following Table 1. In
the case of Comparative Example 1 without adding graphite, the char strength
10 was 75%, but in Experimental Examples 1 to 5 with added graphite, the char
strengths were increased to 80% or more.
(Table 1)
Experimental
Example
Coal
kind
Mixing ratio of coal
briquettes
Hot strength
index
(+10 mm, %)
Char strength
(I600,+10 mm %)
Coals Graphite
Experimental
Example 1
Coal A 90 10 77.7 84
Experimental
Example 2
Coal A 8592 15 91.2 85
Experimental
Example 3
Coal A 70 30 89.0 80
Experimental
Example 4
Coal B 90 10 72.9 85
24
Experimental
Example 5
Coal B 85 15 93.2 86
Comparative
Example 1
Coal A 100 0 12.3 75
Comparative
Example 2
Coal A 60 40 83.8 68
Experiment for measuring hot strength of coal briquettes
according to graphite type
Coal briquettes were manufactured by using kish graphite and
crystalline graphite. In addition, the hot strength of the 5 coal briquettes was
measured.
Experimental Example 6
Coal briquettes were manufactured by using kish graphite that is a byproduct
of an iron making process. Since the kish graphite was generated by
10 precipitating a carbon component dissolved in molten iron, purity and
crystallinity thereof were excellent. The coal briquettes manufactured by
adding kish graphite at 10wt% to coal A was transformed to char. In this case,
a hot strength index of the char of the coal briquettes was 82.7%. Further, an
I-drum strength index representing the char strength was relatively high at 86%.
15 Experimental Example 7
Coal briquettes were manufactured by using crystalline graphite. The
coal briquettes manufactured by adding crystalline graphite at 10wt% to coal A
was transformed to char. In this case, the hot strength index of the char of the
25
coal briquettes at 77.7% was slightly lower than the hot strength index of the
char of the coal briquettes of Experimental Example 6. Further, the I-drum
strength index representing the char strength as 84% was similar to the char
strength of the coal briquettes of Experimental Example 6.
5 (Table 2)
Experimental
Example
Coal
kind
Mixing ratio of coal
briquettes (%)
Hot strength
index
(+10 mm, %)
Char
strength
(I600, +10
mm %)
Coals
Crystalline
graphite
Kish
graphite
Experimental
Example 6
Coal A 90 10 0 77.7 86
Experimental
Example 7
Coal A 90 0 10 82.7 84
Operation experiment of melter-gasifier of coal briquettes
As described above, results verified in an experimental room were
directly applied to a melter-gasifier for manufacturing molten iron. Accordingly,
10 an effect according to application of the melter-gasifier was verified. The
results are represented in the following Table 3.
Experimental Example 8
Coal briquettes including graphite at 2 wt% and using molasses as a
binder was manufactured. An operation was observed by charging the coal
15 briquettes in the melter-gasifier. The operation was continuously performed
and a coal kind and a usage condition of molasses were equally maintained for
26
a continuous operation period. In addition, the hot strength of the coal
briquettes, and a yield of molten iron and fuel cost of the melter-gasifier, were
summarized by average values for the operation period. The hot strength was
represented based on +16 mm, the hot strength was largely increased by
adding the graphite, the yield of molten iron largely increased 5 by improving
permeability and flowage, and the fuel cost was reduced.
Experimental Example 9
Coal briquettes including graphite at 3 wt% and using molasses as a
binder was manufactured. The rest of the experimental processes were the
10 same as those of the aforementioned Experimental Example 8. As an
experimental result, when the graphite was added, the hot strength largely
increased, the yield of molten irons was largely increased, and the fuel cost was
reduced.
Comparative Example 3
15 Coal briquettes using molasses as a binder without adding graphite
were manufactured. The rest of the experimental processes were the same as
those of the aforementioned Experimental Example 8. As an experimental
result, as compared with Experimental Examples 2 and 3, it could be seen that
the hot strength index of the coal briquettes and the yield of molten iron were
20 low.
(Table 3)
Graphite
mixing
Operation
period
Hot strength index
of coal briquettes
Yield of molten
iron
Fuel cost
(kg/t27
ratio
(%)
(day) (+16 mm, %) (t-molten
iron/day)
molten
iron)
Experimental
Example 8
2 21 80.9 2526 737
Experimental
Example 9
3 7 85.9 2429 714
Comparative
Example 3
0 6 67.2 2345 777
X-ray diffraction measurement experiment of graphite-added coal
briquettes
Hot quality of coal briquettes manufactured by adding crystalline
graphite and kish graphite was excellent. Coal briquettes 5 manufactured by
adding graphite were different from coal briquettes without adding graphite in
terms of carbon crystallinity. This could be seen through an X-ray
diffractometry result. That is, 2 value of carbon included in coal was exhibited
at approximately 21 degrees, and as the degree of coalification is increased, the
10 2 value is finely increased.
However, in the coal briquettes adding graphite, a peak was exhibited
around 26.6 degrees. A characteristic of the coal briquettes manufactured
according to experimental examples of the present invention by using a crystal
characteristic of the graphite could be seen. In this case, since SiO2 among
15 minerals configuring coal had a peak in a range close to the graphite, in order to
28
observe the peak of only the graphite, impurities included in the coal briquettes
were removed by pre-processing. A sample of the coal briquettes which are
ground to 63㎛ or less were eluted at 50℃ for 3 hours and then washed using
distilled water. Next, in order to remove SiO2, the coal briquettes was
secondarily acid-treated for 3 hours again in a hydrofluoric acid 5 (HF) solution at
48% heated at 50℃, washed using distilled water, and then dried to
manufacture a sample for analysis. In addition, an X-ray diffraction analysis
was performed by using a copper (CU) target at a speed of 1 degree/min with
an acceleration voltage of 20kV at 100mA.
10 Experimental Example 10
Coal briquettes including graphite of 5wt% were manufactured. The
rest of the experimental processes were the same as those of the
aforementioned Experimental Example 1. A sample for analysis was extracted
according to the aforementioned method.
15 Experimental Example 11
Coal briquettes including graphite at 10wt% were manufactured. The
rest of the experimental processes were the same as those of the
aforementioned Experimental Example 1. A sample for analysis was extracted
according to the aforementioned method.
20 Experimental Example 12
Coal briquettes including graphite are 15wt% were manufactured. The
rest of the experimental processes were the same as those of the
aforementioned Experimental Example 1. A sample for analysis was extracted
29
according to the aforementioned method.
Experimental Example 13
Coal briquettes including graphite of 20wt% were manufactured. The
rest of the experimental processes were the same as those of the
aforementioned Experimental Example 1. A sample for analysis 5 was extracted
according to the aforementioned method.
FIG. 6 illustrates an X-ray diffraction graph of coal briquettes
manufactured according to Experimental Examples 10 to 13 and Comparative
Example 1.
10 As illustrated in FIG. 6, as the X-ray diffraction analysis results of the
coal briquettes, in the case of Comparative Example 1, at a 2 value, there was
no peak at 26.6 degrees. On the contrary, in Experimental Examples 10 to 13,
the peak was exhibited at 26.6 degrees. Further, as the mixing ratio of
graphite increased, the strength of the peak clearly increased.
15 While this invention has been described in connection with what is
presently considered to be practical exemplary embodiments, it is to be
understood that the invention is not limited to the disclosed embodiments, but,
on the contrary, is intended to cover various modifications and equivalent
arrangements included within the spirit and scope of the appended claims.

【Claim 1】
A method for manufacturing coal briquettes which are charged into a
dome part of a melter-gasifier to be rapidly heated in a apparatus for
manufacturing molten iron including the melter-gasifier into 5 which reduced iron
is charged, and a reducing furnace connected to the melter-gasifier and
providing the reduced iron, the method comprising:
providing powdered coals;
providing graphite suppressing hot differentiation of the coal briquettes;
10 providing a hardening agent and a binder;
providing a mixture by mixing the powdered coals, the graphite, the
hardening agent, and the binder; and
providing the coal briquettes by molding the mixture,
wherein in the providing of the mixture, a ratio of the amount of graphite
15 to the sum of the amount of powdered coals and the amount of graphite is
greater than 0 and 0.3 or less.
【Claim 2】
The method of claim 1, wherein the ratio of the amount of graphite to the
20 sum of the amount of powdered coals and the amount of graphite is 0.1 to 0.15.
【Claim 3】
The method of claim 1, wherein the graphite is crystalline graphite or
31
kish graphite.
【Claim 4】
The method of claim 1, wherein in the providing of the graphite, the
graphite is pressure-transported with a gas, stored in a graphite 5 storage bin,
and then provided.
【Claim 5】
The method of claim 4, wherein in the providing of the mixture, the
10 graphite is directly mixed with the hardening agent and the binder while not
mixed with the powdered coals in advance.
【Claim 6】
The method of claim 4, wherein the gas includes nitrogen or a by15
product gas.
【Claim 7】
The method of claim 1, wherein in the providing of the mixture, the
amount of binder increases as the amount of graphite increases.
20
【Claim 8】
The method of claim 1, wherein in the providing of the coal briquettes,
the coal briquettes have an X-ray peak at 26 to 27 degrees when the coal
32
briquettes are under X-ray diffraction analysis.
【Claim 9】
An apparatus for manufacturing coal briquettes, comprising:
a powdered coal storage bin storing 5 powdered coal;
a graphite storage bin storing graphite;
a graphite transport pipe connected with the graphite storage bin and
pressure-transporting the graphite with a gas to the graphite storage bin;
a binder storage bin storing a binder;
10 a hardening agent storage bin storing a hardening agent;
a mixer providing a mixture by mixing the powdered coal supplied from
the powdered coal storage bin, the graphite supplied supplied from the graphite
storage bin, the binder supplied from the binder storage bin, and the hardening
agent supplied from the hardening agent storage bin; and
15 a molding machine receiving the mixture from the mixer to mold the
mixture.
【Claim 10】
The apparatus of claim 9, wherein the graphite storage bin is directly
20 connected with the mixer.